Tubular incandescent lamp



P 7, 1931- K. WIEGAND 1,800,037

TUBULAR I NCANDE SGENT LAMP Filed Nov. 2, 1928 Inventor: Kurt Wie and byw m His Attorney Patented Apr. 7, 1931 UNITED STATES PATENT OFFICE KURT WIEGAND, OF BERLIN, GERMANY, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK TUBULAR IN CANDESCENT LAMP Application filed November 2, 1928, Serial 0.

The invention relates to incandescent lamps with tubular bulbs having a filament extending longitudinally of the bulb, and more particularly to such lamps in which the filament is carried on a filament holder having anchors projecting inwardly from a supporting member such as a wire coil or helix surrounding the filament and bearing against the inner wall of the bulb. In shipping such lamps, which can be made either as straigl t tubes or also as tubes curved to form signs or letters, the filament is sometimes damaged because shocks to the helical supporting member are transmitted from turn to turn and the oscillation and movement thus produced in the helical supporting member cannot alwaysbe followed by the comparatively fine filament stretched on the anchors mounted on said member.

In order to hinder or prevent transmission of shocks within the filament holder and to thus make the support of the filament safer against shocks, part or all of those loops which in effect are, turns of the helical supporting member and which bear against the inner wall of the bulb are, according to the invention, fastened to one or more stay wires running along the inner wall of the bulb. The individual loops of the supporting member may also be made like partial or complete rings and be fastened to one or more stay wires running along the inner wall of the bulb, in which case the supporting member of the filament holder which carries the filament no longer has the shape of a continuous wire helix, but consists of a number of wire loops forming partial or complete rings placed transversely to the glass bulb and bearing against its inner wall and connected to but insulated from one another by one or more longitudinal stay wires. In the latter case use may advantageously be made of loops in the form of semi-circles or half rings instead of complete rings, as then half of the circumference of the tube can be kept free along its entire length from the light obscuring filament holder. 1

Some of the various forms in WhlCh the invention may be embodied are shown in the accompanying drawing in which Flg. 1

316,849, and in Germany November 24, 1927.

shows in elevation a form of tubular lamp with a filament holder having a supporting member with loops arranged to form a helix; Fig. 2 a form with transverse loops instead of helical turns; and Fig. 3 a form with loops in the form of half rings or semi-circles instead of helical turns.

In the particular construction shown in Fig. 1 the filament 1, which may be either a coiled or a straight tungsten wire, is disposed on the filament holder so as to extend along the longitudinal axis of wire loops arranged as a helix 2 which constitutes the sup orting member of the filament holder. 8n the loops of this support the main anchors 5, which project radially inward and support the filament are mounted in glass beads 3, which insulate them from the loops of the wire helix 2. The ends of the filament are secured to leading-in wires 4 hermetically sealed into the walls of the tubular bulb 6. In accordance with the invention there extends along the wall of the bulb 6 a stay wire 7 to which either all or a considerable part of the loops of the helical support 2 are fastened, preferably by being in effect welded to the stay wire by the glass beads 3. The loops of the wire helix 2 are thus stayed or held fast in fixed relation to one another, so that any shocks which may occur cannot be transmitted through and distort the entire helical supporting member. ,Since the separate loops of the helical support are stayed, and since the intermediate anchors 5 may also be directly fixed to the stay wire 7 between adjacent loops of the helix 2, the turns of the helix may be spaced a greater distance apart than where no stay Wires are used, and thereby the light radiation of the lamp in the main radiating direction is considerably improved. The new filament holder may be r de up outside of the tubular bulb, provided with a filament, and then be introduced 'into the bulb.

In the particular form shown in Fig. 2 the filament supporting member has separate wire loops in the form of closed rings 8 which are set transversely to the bulb 6 and, like the loops of the helix 2, bear against the inner wall of the bulb 6. These loops are welded to a longitudinal stay wire 7 preferably by insulating beads 3. In this case there may be provided, in addition to the main anchors 5 on the loops 8, the intermediate anchors 5 fixed directly to but insulated from the stay wire 7 by glass beads welded to the stay wire and to the anchor.

The particular form shown in Fig. 3 differs from that of Fig. 2 only in the use of loops in the form of half rings 9 in place of the loop'in the form of complete or'closed rings 8 shown in Fig. 2. As these half loops 9 are also fitted to the size of the bulb and bear against the inner wall of the bulb 6,

the entire filament holder is likewise sufli ciently supported within the tubular bulb. The light radiationof the tubular bulb is here particularly good since,'in the main radiating direction the bulb is entirely free from any obstruction by parts of the filament holder. The loops whether in the form of helical turns, rings, or half-rings of the supporting member of the filament holder may in some cases, particularly where the tubular bulb 6 is straight, be connected to one another by two or more longitudinal stay wires 7 instead of by only one.

What I claim as new and desire to secure by Letters Patent of the United States is 1- 1. An electric incandescent lamp comprising a tubular bulb, a filament which extends longitudinally of said bulb, and a. filament holder comprising a support consisting of a plurality of wire loops which bear on the inner wall of said bulb and disposed end to end to form a helix, a stay rod connected to and insulated from said loops, and insulated anchors mounted on said stem rod to project radially inward toward the middle of said bulb to-carry said filament.

2. An electric incandescent lamp comprising a tubular bulb, a filament mounted to extend longitudinally of said bulb, .and a filament holder comprising a support composed of a plurality of wire loops set transversely of and fitted into the bore of said bulb, a stay wire connected to but insulated from said loops and extending longitudinally of said bulb, and insulated anchors mounted on said stay wire to project radially inward toward the axis of said bulb to carry said filament.

3. An electric incandescent lamp comprisinga tubular b'ulb, a filament holder comprising a plurality of curved transverse members which bear on the inner walls of said bulb, a longitudinal stay wire connected to but insulated from said members, insulated anchors which project radially inward toward the middle of said bulb, and a filament mounted on said anchors to extend longitudinally of said bulb. I

4. An electric incandescent lamp comprising a tubular bulb, a filament holder having a plurality of transverse members which bear on the inner walls of the bulb, a stay wire connected to but insulated from said members to hold them definitely spaced, insulated anchors mounted on said members and on said stay wire intermediate said members to project radially inward, and a filament mounted on said anchors to extend longitudinally of said bulb. V

5. An electric incandescent lamp comprising a tubular bulb, a filament holder comprising a plurality of bent members set transversely of the bulb to bear on the inner wall of said bulb, a stay wire connected to but insulated from said members at their middle points, insulated anchors mounted on said members to project inwardly to the axis of the bulb, and a filament mounted on said anchors to exend longitudinally of said bulb.

In witness whereof, I have hereunto set my hand this 19th day of October, 1928.

KURT WIEGAND. 

